... I ask then: DID GOD REJECT HIS PEOPLE? By no means! I am an Israelite myself, a descendant of Abraham, from the tribe of Benjamin. God did not reject his people, whom he foreknew. Don’t you know what the Scripture says in the passage about Elijah—how he appealed to God against Israel: “Lord, they have killed your prophets and torn down your altars; I am the only one left, and they are trying to kill me”? And what was God’s answer to him? “I have reserved for myself seven thousand who have not bowed the knee to Baal.” So too, at the present time there is a remnant chosen by grace. And if by grace, then it is no longer by works; if it were, grace would no longer be grace. What then? What Israel sought so earnestly it did not obtain, but the elect did. The others were hardened, as it is written: “God gave them a spirit of stupor, eyes so that they could not see and ears so that they could not hear, to this very day.” And David says: “May their table become a snare and a trap, a stumbling block and a retribution for them. May their eyes be darkened so they cannot see, and their backs be bent forever.” Ingrafted Branches Again I ask: Did they stumble so as to fall beyond recovery? Not at all! Rather, because of their transgression, salvation has come to the Gentiles to make Israel envious. But if their transgression means riches for the world, and their loss means riches for the Gentiles, how much greater riches will their fullness bring! I am talking to you Gentiles. Inasmuch as I am the apostle to the Gentiles, I make much of my ministry in the hope that I may somehow arouse my own people to envy and save some of them. For if their rejection is the reconciliation of the world, what will their acceptance be but life from the dead? If the part of the dough offered as firstfruits is holy, then the whole batch is holy; if the root is holy, so are the branches. Romans 11:1-16
The Prodigal son is ISRAEL and that's it.
What we Gentiles who now are CHRISTIANS have to do is to thank and praise God for His Grace and Mercy and for using people like the apostle Paul in leading us to OBEY GOD.
...I will not venture to speak of anything except what Christ has ACCOMPLISHED THROUGH ME in LEADING THE GENTILES TO OBEY GOD by what I have said and done— Romans 15:1-18